Well swab assembly



Aug. 16, 1966 D. SCARAMUCCI WELL SWAB ASSEMBLY 5 Sheets-Sheet 1 FiledNOV. 24 1961 INVENTOR Dmwae 564 A MUCC/ 6, 1966 D. SCARAMUCCI WELL SWABASSEMBLY 5 Sheets-Sheet 2 Filed Nov. 24, 1961 F15- .14 Fizz-J5 INVENTOR.a 00/145 56% EAMUC'C/ 1956 D. SCARAMUCCI WELL SWAB ASSEMBLY 5Sheets-Sheet 3 Filed NOV. 24, 1961 ill m i -w. 1 I Hi gi a INVENTOR. .2i .L E.- .1 Z 2 .1 E.- .15 DOME-2 ficnenmucaf United States Patent3,266,384 WELL SWAB ASSEMBLY Domer Scaramucci, R0. Box 9125, OklahomaCity 15, Okla. Filed Nov. 24, 1961, Ser. No. 154,528 21 Claims. (Cl.92-192) This invention relates to a swab device for moving a fluid orsemiitluid substance through a tubular passageway. More particularly,but not by way of limitation, the present invention relates to a devicefor swabbing liquid, and to a lesser extent solid particulate materials,from the interior of a tubing string of the type employed in oil wells.

in instances where the reservoir pressure surrounding an oil well hasdropped to a degree such that the natural flow of oil from the well issubstantially decreased, or is altogether stopped, one of the methodsfrequently used to induce further flow for some time without thenecessity of pumping is the agitation of the fluid standing in the wellby swabbing action. Such swabbing action is accomplished by dropping awell swab to the bottom of the production tubing on a wire line. As theswab is lowered through the liquid in the production tubing, theconstruction of the swab allows the liquid to pass upwardly around orthrough the swab. On withdrawing the swab from the well, all liquidabove the swab is lifted thereby up the tubing and out of the well. Byremoving part of the fluid column in the well bore, the bottom holepressure is reduced and more oil and gas will flow rapidly int-o thebore from the surrounding well cavity, thus imparting upward momentum tothe entire column of liquid. The suction effect developed by the swabalso causes the gas in solution in the oil to be released, thus reducingthe average density of the column of fluid and further permitting flow.Once flow is started in this way, it will often continue for some timewithout additional artificial assistance.

Well swabbing of the type described also performs other usefulfunctions, such as the removal of quantities of paraffin which collectin the production tubing and restrict the flow of fluid therethrough -sothat the well is not produced at the optimum rate. Additionally, suchwell swabs are often used to remove drilling fluids from a bore holefollowing completion of drilling operations and before bringing the wellinto production.

Generally, a well swab assembly of the type employed for such swabbingoperations includes a mandrel which is adapted to be suspended from awire line. The mandrel has a fluid passageway therethrough to permitfluid to pass through the mandrel as it is lowered in the productiontubing on the wire line, and a sleeve is slidingly positioned around themandrel to seal this passageway when it is slid down the mandrel towardthe lower end thereof and to open the passageway when it is slid in theopposite direction. A plurality of resilient sealing elements or lipsare bonded to the outer periphery of the sleeve and function to seal offthe production tubing as the swab assembly is drawn upwardly in thetubing. The resilient sealing elements are perhaps the most importantelement of the Well swab assembly in the sense that they are subjectedto rather extreme physical conditions in the operation of the swab, andyet must continue to function properly under all such conditions if theswabbing technique is to be effective to accomplish its intended ends.

The resilient sealing elements must be sufficiently flexible in onedirection so that they offer little or no resistance to the gravitationof the swab assembly down into the production tubing.

On the other hand, a sufficient strength must characterize the sealingelements to permit them to carry a Patented August 16, 1966 very largefluid load to the surface upon withdrawal of the swab from the well.While carrying such fluid loads, the sealing elements must maintain aneffective seal against the internal walls of the production tubing toprevent leakage of the fluid around the swab assembly. Thus, the designof such Well swab assembly sealing element entails the solution of twoproblems requiring seemingly opposite solutions. First, the sealingelements must be suf'ficiently flexible to offer a minimum of resistanceto the downward movement of the swab assembly in the well tubing, and tobe easily biased into sealing contact with the walls of the tubing whenthe swab is withdrawn from the well. Secondar-ily, but of equalimportance, sufficient rigidity or stiffness must characterize suchsealing elements to permit them to lift the enormous fluid loads asrequired.

Further difficulty is presented to the effective functioning of theresilient elements of the swab assembly by the manner in which theproduction tubing is made up or installed in the well. In the firstplace, the diametric dimension of the tubing varies over the length ofthe string. Also the tubing strings generally do not make upconcentrically at the couplings between tubing sections. Egg-shaping ordistortion from circular cross-section at numerous points in the stringis common. Moreover, corrosion deposits and accumulations of scale andforeign matter develop on the inside Walls of the tubing. All of thesefactors result in a very substantial increase in the wear to which theresilient sealing elements of the well swab assembly are subjected asthey contact the tubing during the upward movement of the swab in thewell. -In fact, with the progressive increase in the depth of oil wells,it has become increasingly difficult to make the trip from the bottom ofthe well to the surface without fully wearing out the resilient sealingmembers. Even when such complete destruction dose not occur, asubstantial decrease in the volume of lifted fluid is sustained due toleakage around the sealing elements.

The most serious problem posed by the makeup of the tubing string,insofar as such makeup effects efficient well swabbing, is that which isposed by the recesses, or bore enlargements which occur at each casingcoupling. Usually the inside diameter of each coupling is equivalent tothe outside diameter of the externally threaded tubing sections, and thelength of the couplings is such that a gap of up to about one inchremains between the ends of adjacent tubing sections. Although the endsof the tubing sections usually have an inner bevel, it is usually roughand lacks concentricity, so that the resilient sealing elements of thewell swab assembly are not only subjected to severe wear at this point,but also cannot effectively seal against the irregular tubing walls.Some 30 to 35 couplings are included for every 1,000 fee-t of wellstring. Therefore, several hundred coupling gaps must be traversed bythe sealing elements during each trip from the bottom of the well to thesurface.

That no well swab assembly which has been conceived to datesatisfactorily solves the many problems discussed above is evidenced bythe volumes of material which have been published on the subject and thelarge number of patents which have heretofore been issued upon swab cupsand well swab assemblies. In one type of well swab assembly, the sleevewhich is slidingly fitted around the mandrel and its associatedresilient sealing member is referred to as a swab cup. (This term isalso sometimes applied with less appropriateness of description to othertypes of well swab assemblies.) In such cup-type swab assemblies, along, upstanding lip of resilient material is secured to a metal sleevewhich is slidingly fitted around the mandrel, and the lip defines withthe sleeve a deep pocket or groove which is open at the top to fluidloading. The long, upstanding lips of such cups are made of sufficientlength to permit them to traverse the gap between the ends of coupledtubing sections so that loss of sealing engagement of the lip with thewalls of the tubing is avoided, as is the by-passing of fluid around thelip.

An annular, radially extending heel or base ring is secured to the lowerend of the metal sleeve and supports the resilient sealing lip structureso as to lessen the tendency to extrude the resilient material past thesleeve under conditions of heavy loading. Ordinarily, the resilient lipis constructed of rubber or some similar material.

The upstanding lip type of swab cup is made in two styles. In one ofthese styles, the lip is reinforced by a plurality of reinforcing wireswhich extend from one end of the lip to the other at the outerperipheral surface thereof. In the other style, no wire reinforcement isutilized.

The unreinforced, upstanding lip type of swab cup is utilized inswabbing situations where relatively light loading is anticipated, suchas in shallow wells. This is because the non-reinforced type is moreflexible and pliant than the cup provided with the described reinforcingwires, and is somewhat more eflicient for lifting fluid, provided thatthe load carried does not exceed the supporting ability of theupstanding lip. For swabbing applications involving heavier loading, thewire-reinforced cup is employed. However, having greater rigidity andflexibility, this type of cup requires considerably heavier loading inorder to flex or actuate the lip structure into tight sealing engagementwith the tubing walls, thus usually permitting some fluid to bypass theswab cup at the beginning of the upward movement of the swab in thewell. Since the Wire-reinforced cup is fairly rigid, the upstanding lipstructure must be molded undersizethat is, of lesser diameter than thesmallest diameter encountered in the tubing string. This is in orderthat it will not bear against the walls of the tubing, or if so, onlylightly so as to permit the well swab assembly to fail freely to thebottom of the tubing. The heel or bottom portion of the swab cup must beeven more undersized, since it has very little tendency to contract andpass irregularities in the tubing. Contraction or compression of thisheel portion is yet more limited by the anchorage of the reinforcingwires therein, which anchorage makes the heel structure quite rigid.

Although the wire-reinforced, upstanding lip type of swab cup isrecognized as the most popular now in use and has the greatestload-carrying capacity of all such cups, it presents certain seriousdisadvantages in operation and additionally entails a high cost ofmanufacture. On the other hand, as previously explained, the plain ornon-reinforced type of cup is more eflicient for lighter loads and ischeaper to make. However, it is less durable and is limited in itslifting capacity.

One of the major disadvantages of the wire-reinforced type of swab cupis the propensity of such cups to deposit bits of metal and rubber inthe tubing string due to the shearing off of the reinforcing wires andthe upstanding lips after the cups have been subjected to the great wearinvolved in passing a number of the coupling gaps hereinbeforedescribed. This shearing off results from the bulging outwardly of theupstanding lip by the pressure acting outwardly thereon each time thelip bridges across the gap formed between the ends of the tubingsections where they are connected by the couplings. This condition ofbulging at the coupling gaps causes rapid wear and loss of sealingefficiency. Moreover if the cup is overloaded, complete destruction ofthe plain rubber version can be expected. The wire type on the otherhand will withstand greater abuse early in its wear life, but as thewires are constantly in metal-to-metal frictional contact with thetubing walls, wear is rapid near the mid-point of the wires, creating asubstantial reduction in their cross-sectional area. Thus, in averageoperation, after two or three trips from the bottom of the well to thesurface, the cups must be replaced, even though they are still scaling,in order to avoid the loss of some of the wire elements into the tubingstring. Such loss of the wires into the tubing string necessitates anexpensive clean-out operation and frequently even requires the completepulling of the tubing string and the re-running thereof.

Additionally, with wells currently being drilled deeper and with the newand expanding use of plastic for coating well tubing Walls, the use ofthe wire-reinforced swab cups has presented the new problem of avoidingthe scoring and damaging of such plastic coating by frictional contacttherewith of the wire-reinforcing elements. As a result, the use of suchwire-reinforced swab cups in plastic-coated tubing strings hasconstantly decreased, and the employment of those types of swabassemblies in which the resilient sealing elements contain no wires hasconstantly increased. This increase has been realized in spite of thefact that only limited loads can be handled per trip with the plain ornon-reinforced sealing elements, therefore requiring considerably moretime and expense to swab the well than when the wire-reinforced type ofcups are employed.

Among the more recent efforts to provide an effective swab cup withoutresort to wire-reinforcing elements can be cited the general type ofswab cups disclosed in Webber U.S. Patent 2,633,808, Taylor U.S. Patent2,802,535, and Webber U.S. Patent 2,975,722. The swab cups of the citedtype generally comprise a rubber sleeve which is bonded around theconventional sliding metallic sleeve carried by the swab assemblymandrel and having a plurality of radially extending lip members spacedalong the length of the rubber sleeve. These lip members are generallyquite flexible so that they are able to flip over from a position inwhich they point slightly upwardly in the tubing string to aload-carrying position in which they are inclined slightly downwardly inthe string and contact the interior walls of the string at their outerends. The several lip members are not of sufliciently large diameter tobridge radially across the coupling gaps. Sealing across such couplinggaps is effected by providing enough of the lip members so that some ofthe lip members are sealing against the walls of the tubing string bothabove and below the couplings, even though the lip members in the middledo not extend into contact with the coupling per se.

If the lip members in the multiple lip type of swab cup are madesufficiently thin and flexible, they may be flipped over or inverted anumber of times in passing up and down the tubing string without seriousdanger of rupturing at their base or hinge point where they areconnected to the sleeve of resilient material. On the other hand, if thelip members are made sufliciently thin and flexible to avoid suchfracturing, they are very inefficient and can only be used to lift verylight fluid loads. In general, this type of swab cup will load to onlyabout one-third of the capacity of the wire-reinforced type.

In order to improve the load-carrying capacity of the multiple lip-typeswab cup, cups having lips which are thicker, particularly at the basethereof, and relatively less flexible have been employed. These cups,though having the ability to lift considerably heavier fluid loads, donot withstand the wear to which they are subjected in passing throughthe tubing string as well as the more flexible thin lips previouslydescribed. They also present the great disadvantage of rupturing alongtheir hinge point relatively early during their operating life.

From the foregoing description of the problems encountered in wellswabbing and of the failures of the leading types of previouslydeveloped swab cups to adequately solve all of these problems, it isapparent that a very real need exists in the art for the development ofa swab cup of radical new design which will successfully overcome theproblems discussed in a manner not heretofore effectively accomplished.The present invention presents a novel cocncept in well swab assemblyconstruction, and I have found that well swab assemblies constructed inaccordance with the invention eifectively meet the need for a plainrubber cup having no exposed wire-reinforcing members in associationtherewith. Yet my well swab assembly possesses a load-carrying capacityequivalent to, or greater than, the load-carrying capacity of thewire-reinforced types of swab cups heretofore in use. Moreover, the wellswab assembly in the present invention has been definitely proven tohave greater wear resistance and to greatly outlast the types of suchdevices previously in use. p

In its basic design, a preferred embodiment of the invention comprisesthe usual metallic sleeve or cylindrical member which is slidinglymounted on the mandrel, an annular sleeve of resilient material aroundthe metal cylindrical member and bonded thereto, and an annular,flexible lip of resilient material formed integrally with the sleeve ofresilient material adjacent one end thereof and extending radiallyoutwardly therefrom toward the internal walls of the tubing. The annularsleeve of resilient material has a thick, load-carrying portion which isof lesser diameter than the minimum internal diameter encountered in thetubing string. This thick, load-carrying portion extends from one end ofthe metal cylindrical member over a major portion of the length thereof.The sleeve of resilient material further has a lip-supporting portionwhich is contiguous to, and formed integrally with, the load-carryingportion thereof, and which extends from the load-carrying portion to theopposite end of the metal cylindrical member. The lip-supporting portionof the resilient sleeve is of lesser radial thickness than theload-carrying portion and is the portion of the resilient sleeve whichcarries an annular flexible lip which extends radially outward from thesleeve.

The flexible lip has an outside diameter such that when the lip ispositioned in a plane extending normal to the axis of the well tubing,the lip will establish contact with the internal walls of the tubingsections 12. I11 the basic design of the assembly, the lip occupies thisplane in its relaxed, unstressed state. In certain modified forms of theinvention, the flexible lip extends uwardly at an angle to the axis ofthe tubing and does not contact the walls of the tubing until the lip isbiased into said plane by the impress of the fluid load above the swabassembly. The spacing of the flexible lip from the loadcarrying portionof the sleeve is such that when the well swab assembly is fully loadedhydrostatically, the lip will be biased into sealing engagement with thetubing walls and will simultaneously be placed in abutting contact withthe load-carrying portion of the resilient sleeve.

In the operation of the well swab assembly, the flexible lip offerslittle or no resistance to the downward fall of the swab in the tubingstring. As the swab assembly is pulled upwardly in the string, however,the flexible lip is biased downwardly and outwardly into sealingengagement with the tubing walls by the fluid load above the assembly.Simultaneously, the lip comes to rest upon, and along with the load, issupported by the load-carrying portion of the resilient sleeve. Thisthick loadcarrying portion of the resilient sleeve thus reinforces andsupports the lip and prevents the development of excessive shear forcesacross the hinge line of the lip. An extremely heavy fluid load can becarried by the swab cup assembly without fluid leakage, and yet the thinlip is characterized by suflicient flexibility to allow it to conform toirregularities in the tubing string as they occur.

In order to maintain the fluid seal as the well swab assembly passes thecouplings in the tubing string, it is preferable to employ a pluralityof the swab units disposed in axial juxtaposition along the length ofthe mandrel, or alternatively, to provide a substantially longerresilient sleeve having a plurality of load-carrying portions,lip-supporting portions, and lips tormed thereon in the relation to eachother hereinbefore specified.

When the well swab assemblies of the invention are constructed in thismanner, the flexible lips are provided in suflicient number to permitthe assembly to bridge across the gaps occurring at the tubing couplingswith at least one of the lips in sealing contact with the tubing wallsabove or below the gap.

From the foregoing discussion, it will be perceived that \it is a majorobject of the present invention to provide a relatively inexpensive, yeteflicient and durable well swab assembly for removing liquid and solidparticulate matter from the interior of a string of oil well tubing.

An additional object of the present invention is to provide a well swabassembly which presents only nonmetallic material tor contact with theinternal walls of the well tubing, and yet which is capable ofsupporting a relatively large fluid load.

An additional object of the present invention is to provide a well swabassembly which is not subjected to destructive wear in passing throughthe well tubing to the extent that has been characteristic of previoustypes of swab assemblies.

An additional object of the invention is to provide a well swab assemblywhich is constructed to avoid the subjection of the flexible sealinglips of the assembly to forces tending to shear off or rupture the lipsas the assembly passes by the gaps formed by the couplings of the tubingstring.

Another object of the invention is to provide a well swab assembly whichis positive in its action and yet which may readily pass by obstructionsnormally encountered in the well tubing in which it operates.

A further object of the invention is to provide a well swab assemblywhich may be utilized effectively to raise either light or heavy fluidloads from oil wells of varying depths.

A further object of the invention is to provide a well swab assembly inwhich there is no cup-shaped expansible sealing member which provides acup in which sand or other matter may accumulate so as to interfere withthe proper functioning of the swab assembly.

In addition to the hereinbefore described objects and advantages of thepresent invention, other objects and advantages of the invention,including several modified embodiments thereof, will become apparent andwill be better understood tfirorn a reading of the following disclosurein conjunction with a perusal of the accompanying drawings whichillustrate my invention and certain types of prior art well swabassemblies.

In the drawings:

FIGURE 1 is a vertical sectional view through the center of a well swabassembly of the wire-reinforced type previously used and through atubing string in which the swab assembly is located. The mandrel of theassembly is illustrated in elevation.

'FIGURE 2'is a vew similar to FIGURE 1, but showing a different type ofwell swab assembly which has previously been utilized.

FIGURES 3 through 8 show vertical sectional views through severalembodiments of the present invention. The basic embodiment of theinvention is illustrated in FIGURE 3.

-In FIGURES 9 through 13, the basic embodiment of FIGURE 3 isillustrated in section, as is the mandrel upon which it is mounted. 'InFIGURE 9, the well swab assembly is being lowered into the tubingstring. In FIGURE 10, the swab assembly is shown in the position itassumes as it first commences to ascend the tubing string upon beingpulled 'out of the well. FIGURE 11 shows the swab assembly as it appearswhen fully loaded during its upward movement. FIGURE 12 illustrates theposition assumed by the flexible sealing lip as the swab assembly movesupwardly past a coupling gap in the tubing string. FIGURE 13 illustratesthe position assumed by the flexible sealing lip and the loadcarryingportion of the resilient sleeve of the assembly "Z immediately followingthe traverse of the coupling gap by the lip and the re-establishment ofthe fluid seal.

lF-IGURES 14 and 15 are sectional views illustrating the manner in whichthe modified embodiment of the invention illustrated in FIGURE isutilized for lifting fluid in the tubing string.

FIGURES 16 and 17 are sectional views illustrating the operation of themodified embodiment shown in FIG- URE 7 of the drawings. In FIGURE 16,the well swab assembly is being lowered into the tubing string, while inFIGURE 17, the swab assembly is being withdrawn from the string.

Referring now to the drawings in detail, and particularly to FIGURE 1, atubing string designated generally by reference character 10 comprises aplurality of tubing sections 12 which are interconnected by a coupling14. A gap 16 of approximately one inch or less exists between theopposed ends of the tubing sections 12 and due to the greater diameterof the coupling 14 than each of the tubing sections, the inside diameterof the string 10 is enlarged at the coupling.

In FIGURE 1, a well swab assembly of the upstanding lip,wire-reinforced, cup type is illustrated. A well swab assembly of thistype comprises a cylindrical mandrel 1 8 having a retaining flange 20 atthe lower end thereof and a cup-type swab, designated generally byreference character 22, carried upon the mandrel. The cup-type swabcomprises a metallic cylindrical sleeve 24 which is slidingly mountedupon the mandrel 18 for reciprocation axially upon the mandrel as theswab assembly is moved up and down in the tubing string. The metalliccylindrical sleeve 24 carries a rubber cup 26 which includes a thickheel or base portion 28 and an upstanding lip 30. The upstanding lip 30is normally spaced apart from the metallic cylindrical sleeve 24 so thata groove or pocket 32 is defined between the upstanding lip and themetallic cylindrical sleeve. The dimensions of the upstanding lip 30 aresuch that the lip will span or traverse the gap 16 between tubingsections 12 at the coupling 14.

In the cup-type swab assembly illustrated in FIGURE 1, a plurality ofreinforcing wires 34 are provided around the outer periphery of theupstanding lip 34) and are embedded in the base portion 28 of the rubbercup.

In operation, as the cup-type swab assembly 22 is pulled upwardly in thetubing string 11 the hydrostatic forces exterted by the fluid head abovethe assembly cause the upstanding lip 30 to bellow out into sealingengagement with the internal walls of the tubing. It will be apparentthat at this time the reinforcing wires 34 bear against the internalwalls of the tubing and thus undergo considerable frictional wear. Thewalls of the tubing also are scored by the wires 34 as the swab assemblyis moved upwardly.

The greatest disadvantage, however, of the wire-reinforced swabassemblies occurs as a result of the stresses which act upon theupstanding lip 30 and their reinforcing wires 34 as the swab assemblypasses one of the gaps 16 formed by the tubing couplings 14. As theupper edge or apex of the'upstanding lip 31 first reaches the gap 16,fluid will be bypassed around the swab assembly since the-base portion28 of the rubber cup is undersized and the lip is balanced by equalfluid pressure on both the inner and outer sides thereof. However, whenthe apex of the upstanding lip 30 reaches the lower end of the nextadjacent tubing section 12, a pressure differential is created betweenthe inside and outside surfaces of the lip so that the lip flaresoutwardly. After establishing sealing contact with the internal walls ofthe tubing, the lip is expanded into the gap 16 in the manner shown inFIGURE 1. The portion of the lip 31 bridging the gap 16 is under anextreme load which acts from the inside of the lip and bellows the lipinto the gap. This condition of bulging at the coupling gaps 16 causesrapid wear and deterioration in sealing efliciency and often completedestruction of the cup occurs. This is particularly true where thereinforcing wires 34 have become worn to a thin diameter by theirsliding contact with the internal walls of the tubing string. Since itis necessary to avoid the shearing off of the reinforcing wires 34 andloss of the same into the tubing string, it is usually necessary toreplace the swab assembly after some two or three trips even though theswab is still sealing against the tubing Walls, in order to avoid theloss of the Wire elements into the string.

In FIGURE 2 of the drawings, a dilferent type of well swab assemblywhich has previously been used is illustrated. The left hand side of theview illustrated in FIGURE 2 shows the status of the swab assembly as itis being lowered into the tubing string. On the right hand side of thedrawing, the status of the assembly is shown as it is pulled upwardly inthe tubing string. As in the case of the swab assembly illustrated inFIGURE 1, the type of assembly illustrated in FIGURE 2 also includes thecylindrical mandrel 18 having a flange or retaining shoe 20 at the lowerend thereof and a metallic cylindrical sleeve 24 slidingly positionedaround the mandrel. A sleeve 40 of resilient material is bonded to theexternal periphery of the metallic sleeve 24 and carries a plurality ofsealing lips 42 which are formed integrally therewith and extendoutwardly toward the internal walls of the tubing string. In some typesof swab assemblies, the sealing lips 42 extend, in their normal orunstressed state, in a radial or perpendicular direction with respect tothe axis of the tubing string, while in other types such as that shownin FIGURE 2, the sealing lips extend upwardly at an angle with respectto the axis of the mandrel 18.

As the well swab assembly is lowered into the tubing string 10, theflexible sealing lips 42 offer very little resistance to the gravitationof the swab assembly down the string. All of the lips are in theupwardly extending position illustrated on the left side of FIGURE 2. Asthe swab assembly is pulled upwardly in the tubing string, however, eachlip flips over or inverts under the impress of the fluid load andassumes the position shown by the upper and lower lips 42 on the righthand side of the FIGURE 2. As might be expected, the type of well swabassembly illustrated in FIGURE 2 is relatively inefiicient when carryingheavy fluid loads due to the limited loadcarrying capacity of theflexible lips 42, and actually the swab assembly will load to only aboutone third the capacity of the wire-reinforced type shown in FIGURE 1.The assembly of FIGURE 2, however, does have the important advantage ofeliminating 'the reinforcing wires which, as previously explained,constitute a source of trouble in the later service life of the swabassemblies. It also is subjected to less stress and wear as it passesthe gaps 16 at the tubing couplings 14.

The greatest disadvantage of the swab assembly type illustrated inFIGURE 2 is the tendency of the thin resilient sealing lips 42 torupture at their hinge points, that is, at their intersection or pointof joinder with the resilient sleeve 40, after a relatively short periodof use. This is due to the great number of times the lips 42 are flippedover or reversed in passing up and down the tubing string and across thegaps 16 at the couplings 14.

In FIGURE 3 of the accompanying drawings, a basic embodiment of thepresent invention is illustrated. The conventional cylindrical mandrelconstitutes no part of the present invention except insofar as the samefunctions in combination with the structures illustrated in FIGURES 3through 8, and therefore the mandrel is not shown in any of thesefigures. In the preferred embodiment illustrated in FIGURE 3, a metalliccylindrical sleeve 50 dimensioned to fit slidingly around the mandrel isbonded to an annular sleeve of resilient material designated generallyby reference character 52. The resilient sleeve 52 includes aload-carrying portion 54 which has a tapered lower face 56 to facilitatelowering of the swab assembly into the tubing string, and the resilientsleeve further includes a lip-supporting portion 58 which is of lesserradial thickness than the load-carrying portion 54. The radial thicknessof the load-carrying portion 54 is selected to permit a clearance toexist between the load-carrying portion and the internal walls of thetubing string 10 and the outer surface of the load-carrying portion issubstantially parallel with the inner periphery of the tubing string. Aflexible sealing lip 66 is formed integrally with the lipsupportingportion 58 of the resilient sleeve 52 and extends radially outwardtherefrom toward the walls of the tubing. The flexible sealing lip 60 isrelatively thin and is dimensioned to sealingly engage the internalwalls of the tubing sections 12 when positioned in a plane extendingnormal to the axis of the tubing. In the case of the basic embodiment ofthe invention, this position is assumed by the lip when it is in itsrelaxed, unstressed status.

The operation of the basic embodiment illustrated in FIGURE 3 may bestbe explained by referring to FIG URES 9 through 13 of the drawings. InFIGURE 9, the swab cup assembly is being lowered into the tubing string10 by a conventional wire line (not seen). At such time, the impress ofthe fluid below the swab assembly forces the metallic cylindrical sleeve50 and its associated resilient sleeve 52 upwardly on the mandrel 18 sothat a fluid passageway 64 through the mandrel is opened to permit thefluid in the tubing string 10 to bypass the well swab assembly. It willbe noted that as the swab assembly descends into the tubing string 10,the flexible sealing lip 60 is flexed upwardly slightly by frictionalcontact with the tubing walls. However, the flexibility of the sealinglip 60 is sufliciently great that the frictional resistance of the lipin its contact with the tubing walls does not hinder the gravitation ofthe swab assembly to the bottom of the tubing string 10.

After the swab assembly has reached the bottom of the tubing string 10,its direction of travel is reversed and withdrawal from the string iscommenced. At the instant of reversal and commencement of upward travel,the flexible sealing lip 60 is flexed downwardly into the sealingposition illustrated in FIGURE 10. At the same time, the weight of thefluid column above the well swab assembly forces the metalliccylindrical sleeve 50 and its associated resilient sleeve 52 downwardlyupon the mandrel 18 so that the fluid passageway 64 through the mandrelis closed. The flexibility of the resilient sealing lip 60 is such thatit is sensitive to the lightest fluid loading, and it will almostinstantaneously seal against the internal walls of the tubing at theinstant that downward movement of the well swab assembly is terminated.A positive seal is established between the lip 60 and the walls of thetubing even despite existing irregularities in the wall. The flexibilityof the sealing lip 6G is assured by the provision of the narrow grooveor relief 62 between the lip 60 and the load-carrying portion 54 of theresilient sleeve 52.

Although the thinness and flexibility of the sealing lip 60 assure itscapability of forming a fluid-tight seal with the walls of the tubing,these very characteristics, that is, flexibility and thinness, reduceits load-carrying capacity. I therefore provide a support for flexiblelip 60 when the latter is under heavy hydrostatic loads. It is to thisend that the long, thick, load-carrying portion 54 of the resilientsleeve 52 is provided.

The cooperation between the flexible sealing lip 60 and theload-carrying portion 54 of the resilient sleeve 52 as the sealing lipis subjected to heavy or extreme conditions of hydraulic loading isillustrated in FIGURE 11. The thin flexible sealing lip 60 hassufficient pliability to drop downwardly to the extent necessary and yetmaintain its sealing engagement with the tubing wall. As the sealing lip60 is forced downwardly, the load-carrying portion 54 of the resilientsleeve 52 is placed under compression and is distorted or expandedoutwardly (in What is known as a barreling action) into engagement withthe tubing wall.

It is important to note that the outward expansion of the load-carryingportion 54 of the resilient sleeve 52 is not the direct result of fluidpressure acting above it or at the inner side of the sealing lip 60 asis the case with the conventional upstanding lip-type Well swabassemblies heretofore utilized. Rather, the distortion or expansion ofthe load-carrying portion 54 results from the compressive action of theresilient sealing lip 60 as it is displaced downwardly by thehydrostatic forces of the fluid.

It is also important to understand that the dimensions of theload-carrying portion 54 are such that the frictional engagement betweenthe load-carrying portion and the tubing walls is normally not great andappears to be less than normally occurs in the prior types ofpressureactuated cup versions. In other words, the total extent of theexpansion of the load-carrying portion 54 in a radial direction is notsufficiently great to result in any excessive frictional drag existingbetween the load-carrying portion and the tubing walls as the well swabassembly is pulled upwardly in the tubing string. The relatively slightexpansion of the load-carrying portion 54 is also of advantage in thatthis portion of the swab assembly undergoes a remarkably low rate ofwear and is less apt to be damaged as the swab assembly is pulled pastcertain distortions from concentricity of the tubing string and alsopast scale and paraffin deposits. The slight frictional contact of theload-carrying portion 54 with the internal walls of the tubing thusaccounts in large measure for the relatively long service life of thewell swab assemblies constructed in accordance with the presentinvention.

FIGURE 12 of the drawings illustrates the manner in which the well swabassembly of the invention is pulled past a coupling in the tubing stringwithout being subjected to destructive wear or unbalanced stresses. Thesealing lip 60 of the assembly, though of larger diameter than theinternal diameter of the tubing sections 12, is of lesser diameter thanthe couplings 14 utilized to interconnect adjacent tubing sections.Consequently, as the lip 60 moves upwardly past the upper end of thelower tubing section 12, it snaps upwardly into its normal, unstressedposition. The hydrostatic forces acting upon the upper and lower surfaceof the lip are equalized so that there is no loading on the lip as itenters the coupling gap 16. Since, as previously pointed out, theload-carrying portion 52 is of lesser diameter than the internaldiameter of the sections 12 of tubing, a passageway for the fluid abovethe swab assembly is formed between the loadcarrying portion 54 and thewalls of the tubing when the load-carrying portion is relieved fromcompression by the return of the sealing lip 60 to its normal, unflexedposition.

It is thus apparent that some of the fluid carried above the well swabassembly will be bypassed around the sealing lip 60 and load-carryingportion 54 of the assembly during the time that these elements aremoving across the gap 16 existing at the tubing coupling. However, theloss of fluid at this time is relatively small since the swab is beingpulled upwardly in the tubing string 10 at a relatively great rate ofspeed as compared to the small dimension of the coupling gap 16. Thefluid which is lost in this manner is more than compensated by theconsiderable improvement in load-carrying capacity which is realizedwhen the well swab assembly of the present. invention is employed.Moreover, as will hereinafter ap pear, the basic embodiment of FIGURE 3may be easily modified to provide a duplication of the structure thereshown such that the swab assembly may completely bridge the gap 16formed at the tubing couplings 14 and thereby continuously retain aneffective seal with the tubing walls.

It will be readily apparent from the above discussion that the well swabassembly of the present invention is subjected to a minimum wear anddistortion as it passes across the coupling gaps 16 during its ascent inthe tubing string. This performance constitutes a major improvement overthe upstanding lip type of swab cups previously I l utilized andillustrated in FIGURE 1 of the drawings.

In FIGURE 13, the well swab assembly is illustrated as it appearsimmediately after the flexible sealing lip 60 has traversed the couplinggap 16 and has again sealingly engaged the internal walls of the tubingsection 12. Again the sealing lip 60 has been displaced downwardly intoabutting contact with the load carrying portion 54 of the resilientsleeve 52. It is at this point that a major difference between theoperation of the swab assembly of the present invention and theupstanding lip type of swab assembly of the prior art may be discerned.The only force tending to bellow or barrel outwardly the load-carryingportion 54 of the resilient sleeve 52 into the coupling gap 16 is thatwhich is applied thereto by the downward movement of the flexiblesealing lips 66. There is no internal fluid force acting radiallyoutward upon the load-carrying portion 54 such as occurs in the case ofthe upstanding lip types of Well swab assemblies.

A modified embodiment of the present invention which is designed toimprove the load-carrying capacity of the well swab assembly isillustrated in FIGURE 4. In the modified embodiment of FIGURE 4, aradially extending retaining flange 66 is provided at the base of themetallic cylindrical sleeve 50. The retaining flange 66 functions topermit the assembly to support a substantially increased fluid load, andalso to confine or retain the load-carrying portion 54 of the resilientsleeve 52 against axial distortion. As a result of this confiningfunction of the retaining flange 66, the radial expansion of theload-carrying portion 54 is greater than occurs in the preferredembodiment illustrated in FIGURE 3. Therefore, the increasedloadcarrying capacity of the modified embodiment of the FIG- URE 4 isobtained at some slight sacrifice of low frictional resistance to theupward movement of the well swab asembly as a result of the contactbetween the loadcarrying portion 54 and the' tubing walls.

FIGURE 4a illustrates a slight modification which may be made in theembodiment of FIGURE 4 in order to minimize the pitching off orextrusion of the rubber or material of construction of the load-carryingportion 54 when a retaining flange 66 is employed. The modificationcomprises the provision of a relief or groove 68 which is positioned inthe load-carrying portion 54 just above the retaining flange 66. Thegroove 68 will accommodate the axially displaced mass of theload-carrying portion 54 and will reduce the magnitude of the radialexpansion which the load-carrying portion 54 undergoes when the wellswab assembly is subjected to heavy fluid loading.

It is again importatnt to note that while it is proposed to trap andcompress the flexible sealing lip 60 into tight sealing engagement withthe tubing walls by utilizing the hydrostatic head of fluid over thewell swab assembly, it is desirable to avoid trapping the load-carryingportion 54 between the metal cylindrical sleeve 24 and the tubing wallsany more than is necessary. The primary object of the load-carryingportion 54 is to resiliently support the flexible sealing lip 60. Inother words, the load-carrying portion 54 acts similar to a spring incompression to impart a yielding opposing force to the downwarddisplacement of the flexible sealing lip 64).

As has been pointed out above, the use of a single sealing lip 60 and asingle load-carrying portion 54 results in the disadvantage that thewell swab assembly permits a small portion of the fluid to bypass theassembly as it traverses the coupling gaps 16. In general applicationswhere average fluid loads are concerned, this is not es pecially ofconsequence, as it is the usual practice to install at least two unitsof the type illustrated in FIGURE 3 upon the mandrel 18. Some types ofmandrels space the units, while others provide for stacking the units inabutting relation. On the other hand, the well swab assembly may beconstructed, as shown in FIGURE 5, with a single, elongated, cylindricalmetallic sleeve 70 12 having a surrounding resilient sleeve 72 bondedthereto. The resilient sleeve 72 comprises a plurality of load-carryingportions 74 and lip-supporting portions '76 placed in alternate orconsecutive positions along the length of the metallic cylindricalsleeve 7%. Each of the lip-supporting portions 72 is formed integrallywith a flexible sealing lip 78 which extends radially outward therefromin the manner described above. The relative dimensions of theload-carrying portion 74, lip-supporting portion '76 and flexible lip 78are identical to those hereinbefore specified.

The sealing and load-carrying action of the embodiment illusrtated inFIGURE 5 may best be understood by reference to FIGURES 14 and 15. Froma perusal of these figures, it will be perceived that at least one ofthe flexible sealing lips 78 and its corresponding load-supportingportion 74 is functioning to establish a seal between the internal wallsof the tubing and to support the fluid load, respectively, at all timesduring the passage of the swab assembly by a coupling gap 16. In FIGURE14, the uppermost resilient sealing lip 78 has entered the gap 16 andhas thus resumed its normal, relaxed position. The load-carrying portion74 immediately below the flexible sealing lip 78 is therefore notcompressed so as to undergo radial expansion. The lowermost flexiblesealing lip 78 is, however, subjected to the impress of the fluidthereabove and is flexed downwardly into sealing contact with the wallsof the tubing. The underlying fluid-carrying portion 74 of the resilientsleeve 72 is therefore placed in compression and expands radiallyoutward into light frictional contact with the tubing walls.

In FIGURE 15, the uppermost flexible sealing lip 78 has traversed thecoupling gap 16 and has reestablished sealing contact with tubing walls.It should also be apparent that the load-carrying portion 74 beneath theuppermost sealing lip 78 is compressed and is slightly expanded in aradial direction so that it extends slightly into the coupling gap 16.The lowermost sealing lip 78, on the other hand, is in its relaxedposition, and the loadcarrying portion 74 thereunder has retracted toits normal, unstressed position.

As a further modification of the invention, as many as four of thesealing lips and load-carrying portions may be provided on the resilientsleeve of the well swab assembly to assure longer service life andgreater insurance against the bypass. of fluid around the assembly asthe assembly traverses the coupling gap. Also, as depicted in FIGURE 6,the flexible sea-ling lips, designated by reference character 80, may betapered upwardly at a slight with respect to the axis of the metalliccylindrical sleeve 70, if desired. This construction has the advantageof presenting less frictional resistance to the downward gravitation ofthe well swab assembly in the tubing string 16. In other words, byvirtue of the upward flare of the sealing lips .80, the lips do notcontact with the tubing wall during the descent of the well swabassembly into the tubing string Ill, and a substantial amount of thewear ordinarily encountered in the downward trip is thereby avoided. Theload-carrying portions 82 are, as in the preferred embodiment, of lesserdiameter than the sealing lips and thus may pass irregularities andrestrictions in the tubing string without becoming fouled or subjectedto excessive abrasion.

It will be noted that in the modified emlb'odiment illustrated in FIGURE6, the load-carrying portions 82 of the assembly terminate in a sernilipconfiguration at their upper ends 84. However, this configuration isprimarily [for the purpose of reducing the void or relief 86 whichexists between the load-carrying portions 82. and the flexible sealinglips -80. As previously pointed out, the purpose of the groove or relief86 is to provide the utmost flexibility in the flexible sealing lip 80,and this groove is made as narrow as practicable in order to avoidoverextending the flexible lip '80 as it is forced onto the loadcarryingportion 82. Except for the difference in the ac- 13 tion of the flexiblesealing lips 80 during the downward travel of the well swab assembly,the modified embodiment of the invention depicted in FIGURE 6 involvessimilar operating characteristics to those which have been described inreferring to the embodiment illustrated in FIGURE 5.

In FIGURE 7 of the drawings, yet another modified embodiment of theinvention has been illustrated. Although the principles of operation aresubstantially similar to those which obtain in the case of the FIGUREembodiment, some improvement in overall operating efficiency and lengthof service life is realized as a result of the replacement of themetallic cylindrical sleeve with a helical wire spring 90. The sleeve 92of resilient material is bonded to the periphery of the spring 90 andbetween the convolutions thereof. if desired, the spring 90 may bepositioned more centrally in the mass of resilient material instead ofat the inner periphery thereof as shown in the drawing. Also, as afurther slight innovation of the helical spring-type swab assemblyillustrated in FIGURE 7, a nonextrusion, back-up washer such as thatdesignated by reference character 96 in FIGURE 8 may be utilized ifdesired.

The operation of the helical spring-type swab assembly is illustrated inFIGURES 16 and 17. In FIGURE 16, the swab assembly is shown as it islowered in the tubing string. The sensitive sealing lips 98 are easilydefiected upwardly to permit the assembly to fall freely. Theload-carrying portions 94 of the resilient sleeve 92 afford ampleclearance of the tubing walls, since during the downward trip the springis in its relaxed or extended form so that the load-carryingportion-indeed, the entire resilient sleeve-4s in its molded orunstressed con figuration.

The position assumed by the helical spring-type well swab assembly asthe flu-id load is lifted from the tubing string is illustrated inFIGURE 17. The flexible sealing lips 98 not passing across the coupling:gaps 16 are forced by hydrostatic pressure into sealing engagement withthe internal walls of the tubing section and come to rest upon theirrespective load-carrying portions 94. As fluid loading increases, thespring 90 is compressed and its convolutions are moved closer together.in turn causes the resilient material between the convolutions to beexpanded outwardly in a radial direction. The abutting contact of theload-carrying portion 94 with the walls of the tubing closes theclearance through which the sensitive lip member could be extruded underextreme conditions of wear and pressure.

, -It will be noted that the spacing of the convolutions of the helicalspring 90 is purposely relatively short so as to minimize the expansionof the loadcarrying portions 94 in a radial direction. As previouslypointed out, it is desirable that extreme loading and compression of theloadcarrying portions be avoided since this will result in excessivefrictional contact with the walls of the tubing. As the coils of thehelical spring 90 are compressed, the resilient material trapped betweenthe coils prevents the coils from fully closing or coming in cont-actwith each other. However, the trapped resilient material is highlycompressed between the coils and becomes, in effect, a series of thingaskets which effectively seal against the spring convolutions and themandrel so as to prevent fluid from infiltrating between the mandrel andthe spring as well as providing increased resistance to any fluid forcesacting from within the spring. Thus, the tendency of such forces todistort the mass of resilient material into recesses in the tubing wallsis reduced.

The use of the helical wire spring 90 in the present invention presentsan operating principle which is directly opposed to the operatingprinciple underlying the use of wire members in previously used wellswab assemblies, In such previous well swab assemblies, the wire membersare included in the sealing structure to reinforce the sealing lips' andto provide a controlled resistance to the impress of hydrostatic forces,and yet they must have sufficient flexibility to follow the sealstructure in its movement to and from sealing engagement with the tubingwall. The wire structures of the prior art contemplate the verticalpositioning of such wires in the sealing structure usually in basketform, and such wires are intended to form a supporting bridge for theseal structure to resist undue outward displacement of such structure,as at the time of passing coupling gaps. With this arrangement, theoutward flexure of the wirereinforcing members toward the tubing wallsresults in the opening or increasing of the circumferential spacingbetween such wires. Such increase of spacing between the vertical wiresin turn permits the hydrostatic forces acting from the inside of theupstanding lips an enhanced opportunity to force the lips into thecoupling gaps where they soon become severely worn or damaged. In otherwords, in this previous type of Well swab assembly, thewire-reinforcement members were placed at the outside of the upstandingsealing lips and were intended to provide a direct means for resistingthe displacement and deformation of the lip, rather than for the purposeof improving the control which was maintained over the degree ofdisplacement and deformation of the lip as it was passed into contactwith the tubing wall.

In the present invention, the coil spring which is provided at the innerperiphery of the resilient sleeve or in the center of the body thereof,affords an entirely different functional characteristic than thefunction of the wire members in the previously devised swab assemblies.In the present invention, as the fluid load increases, the spacingbetween the convolutions of the helical spring, which may be said tocorrespond to the spacing between the wire-reinforcing members of theprior art swab assemblies, is decreased as opposed to the increasedspacing occurring in the previous swab assemblies and described above.When the fluid forces acting downwardly on the swab assembly of thehelical spring embodiment of the present invention are slight, thespring is compressed only slightly. Under this condition, although thefluid forces do have some effect in displacing the resilientload-carrying portion outwardly, this effect is minor since theresilient material is exposed to compression only between the open coilsof the spring structure, and hence very little radial displacementoccurs.

As the magnitude of the fluid load increases and the need for a moresubstantial supporting structure for the sealing lip is realized, thefluid forces act to compress the spring to a considerably greaterdegree. This narrows the convolution spacing and increases thecompression of the portions of the resilient material between theconvolutions. The load-carrying portion is radially expanded by theshortening of the spring to provide increased support for the heavierfluid load. Although the hydrostatic forces exerted by the fluid .areeffective, therefore, in shortening the spring, the reaction of theload-carrying portion of the swab assembly is actually a mechanicalresult of the alternation of the status in the spring. This is directlyopposed to the manner of functioning of the previously used, upstandinglip, wire-reinforced type of swab assemblies.

From the foregoing description, it will be apparent that the well swabassembly of the present invention presents a highly novel device forswabbing well tubing more efficiently and over longer operating periodsthan any previously devised type of swab assembly. The principles ofoperation obtaining in the swab assembly of the invention are quitedifferent from any which have previously been relied upon. In all of theembodiments hereinbefore discussed, :a sensitive, flexible sealing lipis immediately responsive to even very slight fluid pressures toestablish a tight seal with the internal walls of the well tubing. Theflexibility of the lip is such that the seal is maintained even ininstances of restrictions, or

, distortions of concentricity, in the tubing string. HOW? ever, thesealing lip is not relied upon to carry the fluid load. For thispurpose, a thick, elongated, resilient loadcarrying element is providedand is positioned with respect to the sealing lip so that immediatelyafter the lip is biased into sealing engagement, the ever-increasingload is borne by the load-carrying portion.

Another important aspect of the invention is the arrangement of thevarious elements of the swab assembly in such a way that the exposedresilient material of the assembly does not undergo any substantial wearas the assembly moves past couplings in the tubing string. Also, littleor no resistance is offered to the downward movement of the assemblyinto the tubing string, and wear of the resilient-sealing andload-carrying elements is minimized during such descent.

Although a number of minor modifications and variations in the basicstructure herein described Will occur to those skilled in the art, thesemodifications and variations may, in most instances, be made withoutdeparture from the basic inventive concepts and principles hereindisclosed for the first time. Therefore, insofar as the novel operatingprinciples of my device may be employed in subsequent modified forms andvariations of well swab assemblies, such assemblies are deemed to beencompassed by the spirit and scope of this invention, except as thesame may be necessarily limited by the appended claims.

I claim:

1. A well swab for swabbing the internal walls of, and lifting fluidfrom, oil well tubing or the like comprising, in combination with saidtubing:

a metallic, generally cylindrical member;

an annular sleeve of resilient material around said metallic, generallycylindrical member and bonded thereto, said sleeve having aload-carrying portion of lesser outside diameter than the internaldiameter of said tubing and extending from one end of said cylindricalmember over a major portion of the length thereof and terminating in anabrupt, annular shoulder, the length of said load-carrying portion beinggreater than the radial thickness thereof, and said sleeve furtherhaving a lip-supporting portion of smaller radial thickness than saidload-carrying portion and extending axially along said cylindricalmember from said load-carrying portion toward the other end of saidcylindrical member;

and an annular, flexible lip of resilient material formed integrallywith said lip-supporting portion and extending outwardly therefromtoward the internal Walls of said tubing, said flexible lip beingdimensioned to sealingly engage the internal walls of said tubing whensaid-lip occupies a plane extending normal to the axis of said tubingand being spaced from the annular shoulder of said load-carrying portionby a distance sufiiciently small to permit said lip to sealingly engagethe internal walls of said tubing when said flexible lip is flexed by ahydrostatic pressure into abutting contact with said shoulder.

2. A well swab as claimed in claim 1 wherein said flexible lip extendsnormal to the axis of said metallic, generally cylindrical member in itsrelaxed, unstressed state.

3. A well swab as claimed in claim 1 wherein said flexible lip extendsat an angle of between 45 and 90 degrees with respect to the axis ofsaid cylindrical member when said lip is in its relaxed, unstressedstate.

4. A well swab as claimed in claim 1 wherein said metallic, generallycylindrical member is a metallic sleeve bonded to the inner peripheralwall of said sleeve of resilient material.

5. A well swab as claimed in claim 1 wherein said metallic, generallycylindrical member is a wire helical compression spring bonded to saidsleeve of resilient material adjacent the inner periphery thereof, andsandtwiching said resilient material between the convolutions of saidspring whereby the compression of said spring compresses the resilientmaterial between said convolutions.

6. A well swab as claimed in claim 1 and further characterized toinclude at least one additional sleeve of resilient material around saidmetal, generally cylindrical member, and having its l0ad-carryingportion positioned in abutting relation to the lip-supporting portion ofsaid first-mentioned sleeve of resilient material, the length of theload-carrying portion of each of said additional sleeves of resilientmaterial being greater than the radial thickness thereof;

and an annular, flexible lip of resilient material formed integrallywith the lip-supporting portion of each of said additional sleeves ofresilient material and extending outwardly therefrom toward the internalwalls of said tubing, said flexible lips each being dimensioned tosealingly engage the internal walls of said tubing when said lipoccupies a plane extending normal to the axis of said tubing and beingspaced from their respective associated load-carrying portions by adistance sufliciently small to permit said lip to sealingly engage theinternal walls of said tubing when said flexible lip is flexed byhydraulic pressure into abutting contact with said load-carryingportion.

7. A well swab as claimed in claim 4 and further characterized toinclude an annular, radially extending flange secured concentrically tosaid metallic sleeve adjacent said one end thereof, said flangeextending into the load-carrying portion of said sleeve of resilientmaterial for limiting axial movement of said load-carrying portiontoward said one end of said metallic sleeve when said supporting portionis subjected to a compressive force acting through said flexible lip ina direction normal to said flange.

8. A well swab as claimed in claim 5 and further, characterized toinclude an annular retainer ring embedded in said load-carrying portionadjacent said one end of said helical compression spring and extendingradially through a major portion of said load-carrying portion from theinner peripheral wall thereof for limiting axial movement of saidload-carrying portion toward said one end of said metallic member whensaid load-carrying portion is subjected to a compressive force actingthrough said flexible lip in a direction normal to said ring.

9. In a well swab for swabbing the inner periphery of, and lifting fluidfrom, oil well tubing and the like, comprising: v

a reinforcing sleeve of a size to be inserted inthe tubing;

an annular, resilient lip bonded around the sleeve and being responsiveto fluid loading created by raising the swab in a tubing containingfluid for flexure into sealing engagement with the inner periphery ofthe tubing; and

an annular body of resilient material secured around the sleeve in aposition to support and be distorted by said lip when said lip is flexedin response tofluid loading, said body having an outer surface parallelwith the inner periphery of the tubing, and the length of said bodybeing of a size to provide a barreling effect when said body is loadedby said lip. to provide engagement of said outer surface with the innerpe; riphery of the tubing.

10. In a Well swab for swabbing the inner periphery of, and liftingfluid from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing;

an annular, resilient lip bonded around the sleeve and being responsiveto fluid loading created by raising the swab in a tubing containingfluid for flexure int-o sealing engagement with the inner periphery ofthe tubing; and

11. In a well swab for swabbing the inner periphery of, and liftingfluid (from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing;

a plurality of annular, resilient lips bonded around the sleeve inspaced relation along the length of the sleeve, each of said lips beingresponsive to fluid loading for flexure into sealing engagement with theinner periphery of the tubing; and

a plurality of annular bodies of resilient material bonded around thesleeve, each body being positioned to support and be distorted by one ofsaid lips when the respective lip is flexed in response to fluidloading, each of said bodies having an outer surface parallel with theinner periphery of the tubing, and the length of each of said bodies,along said outer surface thereof, being greater than the radialthickness of the respective body measured from said outer surfacethereof to the outer periphery of said sleeve.

12. In a well swab for swabbing the inner periphery of, and liftingfluid from, oil well tubing and the like, comprising:

a reinforcing sleeve having an outer diameter less than the innerdiameter of the tubing in which the swab is to be used;

an annular, resilient lip bonded around the sleeve and being responsiveto fluid loading created by raising the swab in a tubing containingfluid for flexure into sealing engagement with the inner periphery ofthe tubing; and

i an annular body of resilient material bonded around the sleeve in aposition to support and be distorted by said lip when said lip is flexedin response to fluid loading, said body having an outer surfacesubstantially parallel with the inner periphery of the tubing, thelength of said body, along said outer surface, being at least twice asgreat as the radial thickness of said body measured from said outersurface to the outer periphery of said sleeve.

13. In combination with a string of tubing, a swab for lifting fluidfrom the tubing, comprising:

a reinforcing sleeve having an outer diameter less than the innerdiameter of the tubing;

an annular, resilient lip bonded around the sleeve and being responsiveto fluid loading created by raising the swab in the tubing for flexureinto sealing engagement with the inner periphery of the tubing; and

an annular body of resilient material bonded around the sleeve in aposition to support and be distorted by said lip when said lip is flexedin response to fluid loading, said body having an outer surfacesubstantially parallel with the inner periphery of the tubing and, inthe relaxed condition of said body, said outer surface being spaced fromthe inner peripery of the tubing a distance less than the radialthickness of said body, the length and radial thickness of said bodybeing sufficient to provide a barreling effect and engagement of saidouter surface with the inner periphery of the tubing when the swab islifting fluid from the tubing.

14. In combination with a string of tubing, a swab for lifting fluidfrom the tubing, comprising:

a reinforcing sleeve having an outer diameter less than the innerdiameter of the tubing;

18 lip of resilient material bonded around the sleeve and beingresponsive to fluid loading for flexure into sealing engagement with theinner periphery of i the tubing; and an annular body of resilientmaterial seoured around the sleeve in a position to support and bedistorted by said lip when said lip is flexed in response to fluidloading, said body having an outer surface parallel with the innerperiphery of the tubing and, in the relaxed condition of said body, saidouter surface being spaced from the inner periphery of the tubing adistance less than the radial thickness of said body, and the length ofsaid body, along said 7 outer surface, being greater than the radialdistance between the sleeve and the inner periphery of the tubing. 1

reinforcing sleeve having an outer diameter less than the inner diameterof the tubing;

an annular, resilient lip bonded around the sleeve and being responsiveto fluid loading for flexure into sealing engagement with the innerperiphery of the tubing; and

an annular body of resilient material secured around the sleeve in aposition to support and be distorted by said lip when said lip is flexedin response to fluid loading, said body having an outer surface parallelwith the inner periphery of the tubing and, in the relaxed condition ofsaid body, said outer surface being spaced from the inner periphery ofthe tubing a distance less than the radial thickness of said body, andthe length of said body, along said outer surface, being at (least twiceas great as the radial thickness of said body measured [from said outersurface to the outer periphery of said sleeve.

16. In combination with a string. of tubing having coupling recessestherein, a swab for lifting fluid from the tubing, comprising:

a reinforcing sleeve having an outer diameter less than the innerdiameter of the tubing;

an annular, resilient lip bonded around the sleeve and being responsiveto fluid loading for flexure into sealing engagement with the innerperiphery of the tubing; and

an annular body of resilient material bonded around 17. In a well swabfor swabbing the inner periphery of,

and

lifting fluid from, oil well tubing and the like, comprising reinforcingsleeve of a size to be inserted in the tubing; and

generally cylindrical mass of un-reinforced resilient material bondedaround the sleeve having its upper and lower ends coterminous with theupper and lower ends of the sleeve; said mass of resilient materialbeing shaped to provide a plurality of vertically spaced lip portionsresponsive to fluid loading as the swab is raised in the tubing forflexure into sealing engagement with the inner periphery of the tubing,and shaped to provide a support portion under each lip portionresponsive to fluid loading of the respective lip portion for distortionradially outward into engagement with the inner periphery of the tubing,each of said support portions having an outer diameter less than theinner diameter of the tubing in the relaxed condition of the supportportion and an outer surface parallel with the inner periphery of thetubing, and said outer surface having a length greater than the radialthickness of the respective support portion measured between said outersurface and said sleeve.

18. In a well swab for swabbing the inner periphery of, and liftingfluid from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing; and

a generally cylindrical mass of un-reinforced resilient material bondedaround the sleeve having its upper and lower ends coterminous with theupper and lower ends of the sleeve; said mass of resilient materialbeing shaped to provide a plurality of vertically spaced lip portionsresponsive to fluid loading as the swab is raised in the tubing forflexure into sealing engagement with the inner periphery of the tubing,and shaped to provide a support portion under each lip portionresponsive to fluid loading of the respective lip portion for distortionradially outward into engagement with the inner periphery of the tubing,each of said support portions having an outer diameter less than theinner diameter of the tubing in the relaxed condition of the supportportion and an outer surface substantially parallel with the innerperiphery of the tubing, and said outer surface having a length at leasttwice the radial thickness of the respective support portion measuredbetween said outer surface and said sleeve.

19. In combination with a string of tubing having coupling recessestherein, a swab for lifting fluid from the tubing, comprising:

a reinforcing sleeve of a size to be inserted in the tubing; and

a generally cylindrical mass of un-reinforced resilient material bondedaround the sleeve having its upper and lower ends coterminous with theupper and lower ends of the sleeve; said mass of resilient materialbeing shaped to provide a plurality of vertically spaced lip portionsresponsive to fluid loading as the swab is raised in the tubing forfiexure into sealing engagementwith the inner periphery of the tub ing,and shaped to provide a support portion under each lip portionresponsive to fluid loading of the respective lip portion for distortionradially outward into engagement with the inner periphery of the tubing,each of said support portions having an outer diameter less than theinner diameter of the tubing in the relaxed condition of the supportportion and an outer surface substantially parallel with the innerperiphery of the tubing, and said outer surface having a length greaterthan the length of each coupling recess in the tubing string.

20. A swab as claimed in claim 11 wherein said annular bodies have asmaller diameter than the diameter of the well tubing and said lips havea larger diameter than said load-carrying portions.

21. In a well swab for swabbing the inner periphery of, and liftingfluid from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing; andagenerally cylindrical mass of un-reinforced resilient material bondedaround the sleeve; said mass of resilient material being shaped toprovide a lip portion responsive ot fluid loading as the swab is raisedin the tubing for flexure into sealing engagement with the innerperiphery of the tubing, and shaped to provide a support portion underthe lip portion res-ponsive to the fluid loading of the lip portion fordistortion radially outward into engagement with the inner periphery ofthe tubing, said support portion having an outer diameter appreciablyless than the inner diameter of the tubing in the relaxed condition ofthe support portion so as not to sealingly engage the tubing and soprovide a bypass of fluid around the swab when the swab is moving downthe tubing, and said support portion having an outer surfacesubstantially parallel with the inner periphery of the tubing, saidsupport portion having a length at least twice the radial thicknessthereof.

References Cited by the Examiner UNITED STATES PATENTS 1,981,262 11/1934Burt 9278 2,109,913 3/1938 Thaheld 309-52 2,687,845 8/1954 Young et al309-51 X 2,711,939 6/1955 Losey 30952 2,913,293 11/1959 Dibley et al30951 3,023,062 2/1962 Waldrop 30952 EDGAR W. GEOGHEGAN, PrimaryExaminer.

KARL I. ALBRECHT, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,266,384 August 16, 1966 Domer Scaramucci It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 5, line 1, for "cocncept" read concept line 42, for "uwardly"read upwardly column 7, line 47, for "exterted" read exerted column 11,line 33, strike out "the" second occurrence; column 12, line 50, for"with respect" read angle with respect column 20, line 19, for "0t" readto Signed and sealed this 1st day of August 1967.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, J r.

Attesting Officer

1. A WELL SWAB FOR SWABBING THE INTERNAL WALLS OF, AND LIFTING FLUIDFROM, OIL WELL TUBING OR THE LIKE COMPRISING, IN COMBINATION WITH SAIDTUBING: A METALLIC, GENERALLY CYLINDRICAL MEMBER; AN ANNULAR SLEEVE OFRESILIENT MATERIAL AROUND SAID METALLIC, GENERALLY CYLINDRICAL MEMBERAND BONDED THERETO, SAID SLEEVE HAVING A LOAD-CARRYING PORTION OF LESSEROUTSIDE DIAMETER THAN THE INTERNAL DIAMETER OF SAID TUBING AND EXTENDINGFROM ONE END OF SAID CYLINDRICAL MEMBER OVER A MOJOR PORTION OF THELENGTH THEREOF AND TERMINATING IN AN ABRUPT, ANNULAR SHOULDER, THELENGTH OF SAID LOAD-CARRYING PORTION BEING GREATER THAN THE RADIALTHICKNESS THEREOF, AND SAID SLEEVE FURTHER HAVING A LIP-SUPPORTINGPORTION OF SMALLER RADIAL THICKNESS THAN SAID LOAD-CARRYING PORTION ANDEXTENDING AXIALLY ALONG SAID CYLINDRICAL MEMBER FROM SAID LOAD-CARRYINGPORTION TOWARD THE OTHER END OF SAID CYLINDRICAL MEMBER; AND AN ANNULAR,FLEXIBLE LIP OF RESILIENT MATERIAL FORMED INTEGRALLY WITH SAIDLIP-SUPPORTING PORTION AND EXTENDING OUTWARDLY THEREFROM TOWARD THEINTERNAL WALLS OF SAID TUBING, SAID FLEXIBLE LIP BEING DIMENSIONED TOSEALINGLY ENGAGE THE INTERNAL WALLS OF SAID TUBING WHEN SAID LIPOCCUPIES A PLANE EXTENDING NORMAL TO THE AXIS OF SAID TUBING AND BEINGSPACED FROM THE ANNULAR SHOULDER OF SAID LOAD-CARRYING PORTION BY ADISTANCE SUFFICIENTLY SMALL TO PERMIT SAID LIP TO SEALINGLY ENGAGE THEINTERNAL WALLS OF SAID TUBING WHEN SAID FLEXIBLE LIP IS FLEXED BY AHYDROSATIC PRESSURE INTO ABUTTING CONTACT WITH SAID SHOULDER.